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IWR1443BOOST: IWR1443Boost - Point Cloud Data

Part Number: IWR1443BOOST
Other Parts Discussed in Thread: IWR1443

Hello Team,

I would like to use the mmwave IWR1443 Boost for shape profiling of an object in a scene.

Related to this I have the following questions:

1. Can the mmWave radar be used for short range (3cm - 5m)? If yes, How do we fine tune it to be in that range. What is the range resolution we can expect in that range.

2. What is the minimum range resolution which we can extract out of raw ADC data or point cloud data.?

3. I want to have a 3D shape profile of object. What is the maximum number of point cloud coordinates I obtain? How to obtain the PCL data?

Kindly let me know how do we achieve the above task.

Regards,

Manishkumar Jain

  • Hi Manish,

    There are various threads on this forum which discuss about close range measurements and minimum range resolution. The sensor can be used to measure from about 4 cm to more that 100m. Range resolution is a function of RF bandwidth and with 4GHz continuous bandwidth, the minimum (i.e. best case) range resolution achievable is 3.75 cm. 

    It is important to distinguish between "Range Resolution" and "Range Accuracy" as these are two different (but related) concepts. The range accuracy could be much better than range resolution and it can be as low as a few 100 microns.

    Please refer to the following threads which talk about close range measurements and also range accuracy and range resolution.

    IWR1443BOOST: Sub-millimeter accuracy distance measurement on a short range (from 5 to 30cm)

    IWR1443: Sensor precision at close range

    Regards

    -Nitin

  • Hello Nitin,

    Thanks for your reply.

    I would like to know if we could do the following.

    I want to use mmwave sensor for profiling a 3D Object in a scene and then use the same information to distinguish various object. As fas as I understand the mmwave sensor is able to return 3D point data for the entire scene.

    Is there a way to get 3D point data just for an object?

    Thanks.

    Regards
    Manish

  • Hi Manish,

    The sensor will return a point cloud of the complete scene in its Field of View. The FOV depends upon the design of the antenna. Please note that mmWave does not work like a scanning LIDAR if that's what you meant by getting point cloud data just for one object. The complete FOV is illuminated with the Radio energy at once and the reflected signal is processed to get the Range, Velocity and Angle of arrival for the various reflections. From the point cloud information, the application can filter out points which fall outside a zone of interest.

    It'll depend upon your application requirements whether the Field of View and angular resolution provided by a single chip are suitable for your mapping or not. The IWR1443BOOST EVM has a 110 degree Azimuth field of view and 30 degree elevation field of view (based on 6dB drop in signal as compared to center). This will become an elliptical FOV if you're mounting the sensor on top of the scene. The angular resolution (ability to detect two objects/points in angle spectrum as two different points) in azimuth direction is 15 degrees and the same in elevation direction is about 57 degrees. Please look at the following thread on a similar topic:

    IWR1443BOOST: Is IWR1443 able to do 3D imaging

    Regards

    -Nitin  

  • Hello Nitin,

    Thanks for your reply.

    Do you have an example of cascading IWR1443 Boost sensor in configiurations of 4 sensors for improved range and accuracy?

    How much accuracy and range resolution we can expect if we have the object placed very near to sensor in range of 0.5 m to 2 m?

    Do we need to change the antenna design to have a narrower FOV? or can it be attained using software?

    Regards

    Manishkumar Jain

  • Hi Manish,

    We don't have a cascading example available right now but a 4-chip cascading reference design is planned for released on TI.com later this year 2018.

    With 4 Chip cascading, you can achieve angular resolution as high as ~1.6 degrees as mentioned in in this video. Range resolution is a function of RF bandwidth and doesn't change for cascading vs non-cascading. With max 4GHz continuous RF bandwidth on the IWR1443, the best case range resolution is about 4cm. As explained in the threads referred earlier, Range accuracy is a function of SNR and could be of the order of a few hundred microns at such short distances as 0.5 to 2m.

    Cascading mainly improves angular resolution, but it also increases maximum range attributing to the TX gain achieved by multiple TX channels transmitting in phase. This improves the SNR of the reflected signal and thus range as well as range accuracy. With 4 chip cascading, the max range can be 300m or beyond, however at very close range like the one you mentioned, such high TX power may introduce near range effects such as multiple reflections which can cause ghosting. So you may want to reduce the TX power to avoid such effects while still getting the high angular resolution with a cascaded system.

    FOV is a function of the physical antenna design.

    Regards

    -Nitin